Process for manufacturing oxalates.



UNITED STATES PATENT OFFICE.

LAUNCELOT W. ANDREWS, OF CHICAGO, ILLINOIS.

PROCESS FOR MANUFACTURING OXALA'IES.

Ho Drawing.

To all whom it may concern Be it known thatI, LAUNonLor W. Aunnnws, acitizen, of the United. States, and a resident. of Chicago, Cook county,and State of Illinois, have invented certain new and useful Improvementsin Processes for lVl'anniiurluring Oxalates, of which the tollowing is aspecification.

The invention relates to the manufacture of alkali o's'alates fromalkali formates. As is well knmvn, sodium or other alkali formats,converted into oxalate by the action of heat, whereby hydrogen gas isill itcd and alkali oxalate is produced. it is the pr it, practice toadd to sodium (or other alkali) formate used, large amounts of: inertsubstances such as sodium carbonate, sodium oaxlatc, charcoalpowder,etc., or to add small. amounts of free alkali, i. (2., sodiunr hydroxid.NaOH, or of potassium hydroxid, KOH. The object of these additions is toincrease the yield of oxalate and to secure better regulation andcontrol of the reaction.

The present invention is based on the discovery of the fact that anadmixture of asmall amount of a suitable arsenate or arsenite(preferably an alkali arsenate or arsenite) to the formats employed inthe process, has a highly beneficial influence, in that it increases theyield of oxalate, renders the reaction less stormy, sudden or turbulentand more easily controlled, and avoids the introduction oflarge amountsof foreign material which must be subsequently sepa rated from theproduct at considerable expense. The recovery of the small amount of.arsenate or arseniterequired under the new process can be readily andinexpensively accomplished.

Ifreferably di or tri-alkali. arsenate is employed, and in accordancewith the preferred process, trisodium arsenate, Na,AsO,, or trisodiumarsenit, Na,,AsO',, is used. Theamount of alkali arsenate or arseniterequireddoes not exceed two or three per cent. of the Wei ht of theformate employed. For example, t e improved process can be carried outas follows i Example: 500 pounds of sodium' formate is intimately mixedwith 12 'pounds' of trisodium arsenate, Na ksQ which may con tain waterof crystallization or may be dry.

Patented Oct. 8, 1918.

Serial No. 26,741.

The mixture is then heated to a suitable temperature, say 380 C., untilthe reaction 56 is complete. The action proceeds steadily and rapidlyuntil near the end, when it becomes somewhat slower.

While trisodium and tripotassium arsenate or arsenite are preferred, andcan be 60 readily recovered in the alkali arsenatcpro duced, the use ofother suitable, soluble arsenatcs or arsnnil'es is pontmnplated andcomprised Within the scope of the invention. The trlbasic arsenates orarsenitc of the connuon alkali metal smlinm and potassiul'n ran readilyrectum-red by treat ing the product of the reaction with a relativelysmall amount of water. In this way the arsenate or arsenite useddissolved stood as designating a-chemical compound 39 containing theradicals characteristic of arsenic acid,H,,( As(),), or of arseimusacid. H (As(),,), and it is recognized that the properties which makethese compounds suitable for the purpose of the hereirn'le scribedinvention are mainly due to these acid or negative groups and onlysubordinately to the other elements present in said compounds.Certainarsenates or arsenites,

however, cannot be used to advantage in the improved process. These arethe salts of bases which interfere with or act as anticatalyzers of thedesired reaction, as for example, nickel arsenate or arsenite.

It is obvious that changes may be made in the details set forth withoutdeparture from the essentials of the invention as defined in theclaims.

I claim as my invention 1. The which consists in heating a mixture offor mates and catalytic salts containing the acid radicalscharacteristic of the acids of arsenic.

2. The process of manufacturing alkali 105 oxalate, which consists inheating alkali a as catalyzerfor a'subsequent 75 roccss of manufacturingoxalates metal formats admixed with a catalytic salt of an acid ofarsenic.

3. The process of manufacturing alkali oxalate, which consists inheating alkali 5 metal for-mate admixed with an alkali metal salt of anacid of arsenic.

4. The process of manufacturing sodium oxalate which consists in heatingsodium formate admixed with tri-alkali salt of an oxy-acid of arsenic.

5, The process of n'ianufacturing formats which tonslsl'h in heatingfol'mato admixed with a relatively amount arsenic.

LAUNCELOT W. ANDREWS.

